Drywall as used in the form of panels for interior walls consists of an inner core of gypsum plaster between two outer layers of paper or a mixture of paper and wood fibers. Interior walls of buildings, including residential, commercial and industrial buildings, typically are made of drywall panels nailed to wood or metal studs, drywall having largely replaced plaster for this purpose. Drywall is sold in various panel sizes, such as 4 ft. by 8 ft., 10 ft. or 12 ft. long and the long edges of the panels are positioned horizontally in a wall installation. The joint between the abutting horizontal edges of two drywall panels must be filled with an appropriate joint compound in order to hide the joint between the two panels and develop a flat wall surface from floor to ceiling. The edges of drywall panels to be finished with the joint compound are formed to include a shallow recess along their respective edges and may have a round end or flat end depending on whether the drywall is to be installed on wood studs or metal studs.
The prior art methods and materials utilized for finishing the joint between drywall panels is described in the detailed description which follows and illustrated in the drawings. Ou analysis indicated several disadvantages with the prior art drywall joint finishing techniques: a significant degree of shrinking of the known joint compounds, the necessity of using paper tape or fiberglass tape along a joint finished by the prior art techniques, and the rather low bond strength exhibited by prior art joint compounds. Accordingly, the principal objectives of the development program that culminated in the present invention were to develop a new system for finishing the joints between drywall panels, develop a new joint compound having a higher bond strength than known compounds, and develop a drywall joint finishing system that would eliminate the necessity to use paper o fiberglass tape along the joint. These and other more specific objectives will become apparent from the detailed description which follows.